For a long time ago, a computer connected to the Internet had an RV770 ATI card and used to use the proprietary fglrx driver. Yes… That was my pc…
Then the latest fglrx (10.2) wasn’t compatible with the latest kernel (2.6.33) and that kernel supported Kernel Mode Setting (KMS) using the radeon driver. Debian also started to have appropriate libdrm and Xorg (+ driver).
So I switched to radeon/KMS driver… At first everything was not working and I blamed the radeon driver. However, as it was proved, even after uninstalling the fglrx driver it kept causing me problems. A couple of files were left behind and there was at least one file left diverted to the fglrx’s one. To fix this problem one needs to examine diversions (dpkg-divert –list), use debsusm (e.g. debsums -s libgl1-mesa-glx) and reinstall the packages with checksum problems.
Finally, after switching to radeon/KMS the following things changed:
- The used memory after startup reduced from about 2.5-3GB to less than 500MB (!!!!). I’m not talking about card’s mapped memory. I’m talking about system’s memory.
- Everything runs a lot faster. It looks like system latency is greatly reduced. There are two kind of improvements: (a) KDE’s desktop effects are smoother and (b) it looks like the latency is reduced. Somehow the effects seem to run faster because there is less delay.
- I stopped getting crashes of plasma when logging-in.
- KDE’s effects stopped being disabled every now and then.
- Tearing disappeared (!).
- Compositing effects seem to use less CPU.
- Some sound-card issues disappeared. Every now and then the sound was muted after system startup, but not any more.
So yeah… I really suggest that you switch to radeon/KMS if you’re using the fglrx driver. It sucks.
BTW, I also tested that to a laptop with an older ATI card and it had most of the above improvements as well. A colleague of mine also switched to opensource driver and show the exact same, dramatic reduce of memory usage.